Fluid Processing

ABSTRACT

Fluid processing apparatuses and systems are disclosed. In some embodiments the fluid processing apparatuses include a movable enclosure, a plurality of filter housings disposed substantially within the movable enclosure, and a stand disposed within the enclosure. The filter housings are in fluid communication with one another. Each filter housing defines an elongate path and is configured to support a respective filter along the elongate flow path to filter a substantially continuous flow of fluid. The stand supports each filter housing such that the elongate flow path of each filter housing is substantially parallel to a vertical axis, wherein each filter housing is independently rotatable, relative to the stand.

CLAIM OF PRIORITY

This U.S. patent application is a continuation of and claims priority toU.S. patent application Ser. No. 12/702,602, filed Feb. 9, 2010, whichclaims priority under 35 U.S.C. §119(e) to U.S. Provisional Application61/151,053, filed on Feb. 9, 2009. The disclosures of each of theforegoing are considered part of the disclosure of this application andare hereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure relates to fluid processing systems and relatedcomponents and methods.

BACKGROUND

Mixing is a process in which two or more substances are combined whilethe chemical properties of each substance remain unchanged. Theproperties of the overall mixture, however, can differ from those of thecomponent substances. Thus, mixing is often used to produce a mediumwith a desired set of physical and chemical properties.

For example, in semiconductor fabrication, chemical mechanicalplanarization (CMP) is used to make wafer surfaces flat. This processrequires slurry of abrasive particles dispersed in a chemicallycorrosive agent. During CMP, movement of the abrasive particles on thewafer mechanically removes material from the wafer surface.

The chemically corrosive agent of the slurry facilitates this mechanicalremoval of material by reacting with the material to be removed. Toproduce CMP slurry having desired properties, it can be useful to filterthe CMP slurry to achieve the desired distribution of abrasive particlesdispersed within the chemically corrosive agent.

SUMMARY

In one aspect of the invention, a fluid filtration apparatus includes amovable enclosure and a first plurality of filter housings disposedsubstantially within the movable enclosure. The first plurality offilter housings are in fluid communication with one another, and eachfilter housing is configured to support a filter therein to filter asubstantially continuous flow of fluid.

In another aspect of the invention, a fluid filtration system includes amaterial feed, a flow controller, a pump, and a fluid filtrationapparatus. The flow controller is in fluid communication with thematerial feed and a processing stream. The pump is in fluidcommunication with the material feed and the flow controller and isconfigured to move material from the material feed to the flowcontroller. The fluid filtration apparatus is in fluid communicationwith the pump. The fluid filtration apparatus includes a movableenclosure, a first plurality of filter housings, and a first pluralityof filters. The first plurality of filter housings is disposedsubstantially within the movable enclosure and each filter housing ofthe first plurality of filter housings is in fluid communication withone another. Each filter of the first plurality of filters is supportedin a respective filter housing to filter a substantially continuous flowof fluid.

Embodiments can include one or more of the following features.

In some embodiments, each filter housing is configured to be releasablydetachable from the respective filter supported therein.

In certain embodiments, the filter housings are in fluid communicationin series with one another to receive a substantially continuous flow offluid. In some embodiments, the first plurality of filter housings isconfigured to support filters having different pore sizes. In certainembodiments, the plurality of filter housings are configured to supportfilters having progressively smaller pore sizes in the direction of thesubstantially continuous flow of fluid.

In some embodiments, each filter housing is configured to support afilter cartridge. In certain embodiments, each filter housing isconfigured to support an open-end cartridge.

In certain embodiments, the plurality of filter housings are arranged inparallel with one another such that each filter housing receives atleast a portion of a substantially continuous flow of fluid. In someembodiments, the plurality of filter housings are configured to supportfilters having substantially the same pore sizes.

In some embodiments, the movable enclosure includes a plurality ofwheels for moving the fluid filtration apparatus, the plurality offilter housings disposed substantially within the movable enclosure,above the plurality of wheels. In certain embodiments, at least one ofthe plurality of wheels is lockable in place.

In certain embodiments, the movable enclosure comprises at least onepanel removable to provide access to at least one filter housing.

In some embodiments, the movable enclosure includes at least one doorconfigured to provide access to at least one filter housing. In certainembodiments, the movable enclosure defines a substantially cuboid volumeand the movable enclosure includes a door on more than one side (e.g.,each side) of the cuboid.

In certain embodiments, the fluid filtration apparatus includes an inletconduit passing through the movable enclosure for fluid communicationwith the first plurality of filter housings. In some embodiments, thefluid filtration apparatus includes a quick disconnect coupling disposedon the inlet conduit to establish fluid communication between the inletconduit and a supply of a substantially continuous flow of fluid.

In some embodiments, the fluid filtration apparatus includes an outletconduit passing through the movable enclosure for fluid communicationwith the first plurality of filter housings. In certain embodiments, thefluid filtration apparatus includes a quick disconnect coupling disposedon the outlet conduit to establish fluid communication between theoutlet conduit and a processing stream for receiving a substantiallycontinuous flow of fluid.

In certain embodiments, at least a portion of the movable enclosure istransparent. In some embodiments, at least a portion of the movableenclosure is poly(methyl methacrylate).

In some embodiments, the movable enclosure is dimensioned to fit withina size envelope with a height of about 50 inches, a width of about 40inches, and a length of about 40 inches.

In certain embodiments, the fluid filtration apparatus includes aflexible tube extending between each of the filter housings to establishfluid communication between each of the filter housings.

In some embodiments, the fluid filtration apparatus includes a pluralityof quick disconnect couplings disposed on each respective filter housingfor connecting the filter housing to the respective filter tube.

In certain embodiments, each filter housing has an inlet portion and anoutlet portion, each filter housing defines an elongate path between theinlet portion and the outlet portion, and each filter housing isconfigured to support the respective filter along the elongate flowpath. In some embodiments, each filter housing is configured to receivea filter through at least one of the inlet portion and the outletportion. In some embodiments, the fluid filtration apparatus, includes astand disposed within the enclosure, the stand supporting each filterhousing such that the elongate flow path of each housing issubstantially parallel to a vertical axis. In certain embodiments, eachfilter housing is independently rotatable relative to the stand about ahorizontal axis. In some embodiments, each filter housing isindependently rotatable relative to the stand about a horizontal axis toform about a 45 degree angle between the elongate flow path of therespective filter housing and the vertical axis. In certain embodiments,the fluid filtration apparatus includes a plurality of sensors, eachsensor disposed on a respective filter housing and in fluidcommunication with each respective filter housing. Each sensor extendsaway from the stand at an angle with respect to the respective elongateflow path. In some embodiments, the stand is rotatable about a verticalaxis to move the first plurality of filter housings relative to themovable enclosure. In certain embodiments, the stand is lockable inplace relative to the movable enclosure.

In some embodiments, each filter housing is polyvinyl chloride.

In certain embodiments, each filter housing is stainless steel.

In some embodiments, each filter housing defines a substantiallycylindrical volume. In certain embodiments, the substantiallycylindrical volume has an inner diameter of greater than about 2.5inches and less than about 18 inches. In some embodiments, thesubstantially cylindrical volume has a length of greater than about 1inch and less than about 50 inches.

In certain embodiments, each filter housing is configured to support asingle open end filter cartridge.

In some embodiments, each filter housing is configured to support adouble open end filter cartridge.

In certain embodiments, each filter housing is configured to support anO-ring type filter.

In some embodiments, the fluid filtration apparatus includes a secondplurality of filter housings and a valve switch in fluid communicationwith each of the first plurality of filter housings and the secondplurality of filter housings. The valve switch is configured to direct asubstantially continuous flow of fluid between the first plurality offilter housings and the second plurality of filter housings.

In certain embodiments, the valve switch is a two-way valve.

In some embodiments, the fluid filtration apparatus includes a firstplurality of sensors and a second plurality of sensors. The firstplurality of sensors are each configured to measure a fluid parameterand each in fluid communication with a volume defined by a respectivefilter housing of the first plurality of filter housings. The secondplurality of sensors are each configured to measure a fluid parameterand each in fluid communication with a volume defined by a respectivefilter housing of the second plurality of housings.

In some embodiments, the fluid filtration apparatus further includes acontroller in electrical communication with the first and secondplurality of sensors. The controller is configured to receive a measuredfluid parameter from the sensors, and activate the valve switch based ona comparison between the measured fluid parameter and a threshold value.The activation of the valve switch redirects the substantiallycontinuous flow from the first plurality of filter housings to thesecond plurality of filter housings. In certain embodiments, thecontroller is further configured to send an alarm signal to indicate theneed for maintenance of the first plurality of filter housings. In someembodiments, the controller is further configured to indicate whichfilter housing of the first plurality of filter housings requiresmaintenance. In certain embodiments, the controller is furtherconfigured to compare the valve switch position to signals received fromthe plurality of sensors to determine an alarm condition. In someembodiments, each sensor is configured to measure pressure of fluid inthe respective first and second plurality of filter housings. In certainembodiments, the controller is configured to determine the pressure dropacross each filter supported in the respective filter housing. In someembodiments, each sensor is configured to measure large particle countof fluid in the respective first and second plurality of filterhousings. In some embodiments, each sensor is configured to measureconductivity of fluid in the respective first and second plurality offilter housings. In certain embodiments, each sensor is configured tomeasure pH level of fluid in the respective first and second pluralityof filter housings.

In certain embodiments, the fluid filtration apparatus further includesa plurality of filters, each filter supported in a respective filterhousing to filter a substantially continuous flow of fluid. In someembodiments, each filter housing is configured to be releasablydetachable from the respective filter supported therein.

In some embodiments, the first plurality of filter housings supportfilters having progressively smaller pore sizes in the direction of thesubstantially continuous flow of fluid. In certain embodiments, eachfilter has a pore size of greater than about 0.05 microns and less thanabout 200 microns. In some embodiments, each filter has a pore size ofgreater than about 0.1 microns and less than about 10 microns. Incertain embodiments, each filter has a pore size of greater than about0.2 microns and less than about 1 micron.

In some embodiments, the pump includes a diaphragm pump. In certainembodiments, the diaphragm pump is a bladder pump. In some embodiments,the diaphragm pump is an electro-mechanical diaphragm pump.

In certain embodiments, the flow controller is an adjustable orifice.

In some embodiments, the flow controller is a U-tube flow controller.

In certain embodiments, the fluid filtration system includes a pluralityof flow controllers. Each flow controller is individually adjustable toachieve a target flow rate of the substantially continuous flow offluid.

In some embodiments, the fluid filtration system further includes anin-line mixer in fluid communication with the pump and the fluidfiltration apparatus. The in-line mixer is disposed between the pump andthe fluid filtration apparatus.

Other aspects, features, and advantages will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a slurry blending plant with a filterstation disposed between a product packaging station and a series ofin-line mixers.

FIG. 2 is a schematic view of the filter station of FIG. 1.

FIG. 3 is a schematic of a filter housing of the filter station of FIG.1 tilting about a horizontal axis during filter replacement.

FIG. 4 is a schematic of a stand of the filter station of FIG. 1rotating about a vertical axis during repositioning of the filterstation.

FIG. 5 is a schematic of inputs to and outputs from a controller of theplant of FIG. 1.

FIG. 6 is a flow chart of a process used to control the position of avalve switch of the filter station of FIG. 1 based on pressuremeasurements received from pressure sensors in communication with acontinuous flow of slurry through the filter station.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, a continuous slurry blending plant 10 includes amixing station 12, a filter station 14, and a product packaging station31. The filter station 14 is positioned along a processing stream 29,between the mixing station 12 and the product packaging station 31. Asdescribed below, the filter station 14 includes a first filter set 30, asecond filter set 32, and a valve switch 34 in fluid communication withthe first and second filter sets 30, 32 to direct a continuous flow ofslurry to either the first filter set 30 or the second filter set 32.

During use, the mixing station 12 mixes raw materials to form asubstantially continuous flow of slurry that moves toward the filterstation 14, along the processing stream 29. At the filter station 14,cartridge filters 49 positioned in the first and second filter sets 30,32 remove agglomerated particles and/or impurities from the slurry. Thefiltered slurry then flows to the product packaging station 31 where,for example, the slurry can be used in CMP of wafers or packaged for useat another location. As described below, the blending plant 10 controlsthe position of the valve switch 34 such that maintenance (e.g., filterchanges) can be performed on one filter set (e.g., the first filter set30) while slurry continues to flow through the other filter set (e.g.,the second filter set 32). The on-line maintenance facilitated by filterstation 14 can reduce the amount of operational downtime required formaintenance. The on-line maintenance facilitated by the filter station14 can also improve the yield of wafer production, for example, byreducing the likelihood that agglomerated particles will reach andinterfere with downstream processes performed at the product packagingstation 31.

The substantially continuous processing carried out by the blendingplant 10 can have a higher volume throughput and/or require less spacethan a plant relying on batch processing. Additionally or alternatively,by reducing start and stop operation characteristic of batch processing,the blending plant 10 reduces slurry shearing and, thus, reduces thelikelihood of particle agglomeration resulting from such shearing. Asalso described below, the filter station 14 is movable to facilitateassembly and/or reconfiguration of the blending plant 10.

The mixing station 12 includes material feeds 13, 15, 16, 17, pumps 18,19, 20, 21, flow controllers 22, 23, 24, 25, and mixers 27. Each pump18, 19, 20, 21 is disposed between a respective material feed 13, 15,16, 17 and a respective flow controller 22, 23, 24, 25. The mixers 27are in-line pipe mixers positioned in series along the processing stream29, and each mixer 27 includes baffles for inducing swirl (e.g., dualswirl) into the flow of materials introduced into the processing stream29 through the flow controllers 22, 23, 24, 25. Each mixer 27 ispositioned downstream of a corresponding flow controller 22, 23, 24, 25such that there is a respective mixer 27 downstream of each materialfeed 13, 15, 16, and 17.

Material feeds 13, 15, 16, 17 each provide an inlet for receiving rawmaterial to be combined into slurry. Material feed 13 receives thechemically corrosive agent that acts as the dispersion medium of theslurry. Slurry components, such as abrasive particles, are introduceddownstream, through material feeds 15, 16, 17. A single raw material canbe introduced through more than one of the material feeds 13, 15, 16, 17to stratify the raw material along the processing stream 29 which can,for example, improve mixing quality.

Each pump 18, 19, 20, 21 moves a raw material from a respective materialfeed 13, 15, 16, 17 through a respective flow controller 22, 23, 24, 25.Pumps 18, 19, 20, 21 can be electro-mechanical diaphragm pumps includinga sealed diaphragm with one side in fluid communication with the workingfluid and the other side in communication with a motor drive. Fluid ispumped as the motor drive flexes the diaphragm.

Each flow controller 22, 23, 24, 25 includes an adjustable orifice andan internal regulating valve that maintains a constant pressure dropacross the orifice to achieve a constant volumetric flow rate. Thevolumetric flow rates through the flow controllers 22, 23, 24, 25 areindependently adjustable such that the raw materials can be combined indesired proportions. For example, the volumetric flow rates through theflow controllers 22, 23, 24, 25 can be adjusted to achieve a targetconcentration of abrasive particles dispersed within the chemicallycorrosive agent.

Referring to FIGS. 2-3, the filter station 14 includes the first filterset 30, the second filter set 32, the valve switch 34, a stand 36, anenclosure 38, an inlet conduit 42, and an outlet conduit 44. The filtersets 30, 32 are supported by the stand 36 within the enclosure 38. Theinlet conduit 42 and the outlet conduit 44 each pass through theenclosure 38 to allow the substantially continuous flow of slurry topass through the filter station 14. The inlet conduit 42 and the outletconduit 44 each include a respective quick disconnect coupling 43 thatcan facilitate connection and disconnection of the filter station 14 tothe processing stream 29. Each filter set 30, 32 is in fluidcommunication with the valve switch 34 and the outlet conduit 44. Thevalve switch 34 is in fluid communication with the inlet conduit 42 suchthat, during use, the substantially continuous flow of slurry flowingthrough the inlet conduit 42 can be directed through either filter set30, 32 for filtering.

The enclosure 38 is substantially cuboid and includes wheels 58. Thecuboid shape can facilitate assembly, disassembly, and/or partialdisassembly of the enclosure 38. Of course, the enclosure 38 can beother shapes other than cuboid. For example, the enclosure 38 can becylindrical, pyramidal, conical, frusto-conical, and/or spherical.

The enclosure 38 has a size envelope of less than approximately50″×40″×40″. Filter station 14 can be moved on wheels 58 as necessary toconstruct plant 10 within an available footprint. The enclosure 38 canprotect filter sets 30, 32 from damage as the filter station 14 ismoved. Additionally or alternatively, the enclosure 38 can protectnearby operators and equipment during operation of the plant 10. Theenclosure 38 is transparent plastic (e.g., poly(methyl methacrylate)) tofacilitate visual inspection of filter station 14 during operation. Thevolume defined by the enclosure 38 is accessible from each side and fromthe top (e.g., through removable panels and/or doors) to facilitateaccess to components disposed within the enclosure 38 (e.g., filter sets30, 32) during maintenance.

The filter sets 30, 32 are substantially identical. For the sake ofclarity, components specific to filter set 30 are identified byreference numerals ending in “a,” and components specific to filter set32 are identified by reference numerals ending in “b.”

Each filter set 30, 32 includes three elongate filter housings 46 a,b,47 a,b, 48 a,b, three pressure sensors 50 a,b, 51 a,b, 52 a,b, and threecartridge filters 49. Each filter housing 46 a,b, 47 a,b, 48 a,b has aninlet portion 54 and an outlet portion 56 and defines an elongate flowpath therebetween. For clarity of illustration, the inlet portion 54 andthe outlet portion 56 is shown only for the filter housing 46 a. Filterhousings 46 b, 47 a,b, 48 a,b have analogous inlet and outlet portionswhich may be reversed with respect to the inlet portion 54 and theoutlet portion 56 of the filter housing 46 a. For example, the inletportion of filter housing 47 a may be arranged proximate to the outletportion 56 of filter housing 46 a.

A respective cartridge filter 49 is removably disposed along theelongate flow path defined by each filter housing 46 a,b, 47 a,b, 48a,b. Each pressure sensor 50 a,b, 51 a,b, 52 a,b is in fluidcommunication with a respective elongate flow path defined by arespective filter housing 46 a,b, 47 a,b, 48 a,b to measure the pressuredrop of the substantially continuous flow of slurry passing through thecartridge filter 49 disposed in the filter housing. For example, thepressure drop across filter housing 46 a can be measured as thedifference between the pressures measured at pressure sensors 50 a and51 a. Each measured pressure drop can indicate that the cartridge filter49 disposed within the respective filter housing 46 a,b, 47 a,b, 48 a,bis clogged and/or otherwise rendered ineffective for filtering theslurry.

The cartridge filters 49 are substantially cylindrical with a length ofabout 30 inches and an outer diameter of about 2.5 inches such that eachcartridge filter 49 substantially fills the dimensions of the elongateflow path of each filter housing 46 a,b, 47 a,b, 48 a,b. The cartridgefilters 49 can be single open end, double open end, and/or O-ring typefilters. The pore size of the cartridge filters 49 can be greater thanabout 0.05 microns and/or less than about 200 microns (e.g., greaterthan about 0.1 microns and/or less than about 10 microns, greater thanabout 0.2 microns and/or less than about 1 micron).

Within each filter set 30, 32, the respective filter housings 46 a,b, 47a,b, 48 a,b are in fluid communication in series. For example, when thevalve switch 34 directs slurry through a given filter set 30, the slurryenters filter housing 46 a, runs through filter housings 46 a, 47 a, 48a in succession, and then exits filter housing 48 a into the outletconduit 44. In this successive arrangement, the cartridge filters 49disposed in respective filter housings 46 a,b, 47 a,b, 48 a,b haveprogressively smaller pore sizes such that the pore size of thecartridge filter 49 disposed in filter housing 47 a,b is less than thepore size of the cartridge filter 49 disposed in the respective filterhousing 46 a,b and greater than the pore size of the cartridge filter 49disposed in the respective filter housing 48 a,b. This arrangement ofsuccessively less porous cartridge filters 49 can allow the more porouscartridge filters 49 to remove particles that could otherwise damageand/or significantly clog the less porous downstream filter(s). Thus,this successive arrangement of cartridge filters 49 can increase theamount of time between filter changes, resulting in both time and costsavings.

In each filter set 30, 32, the respective filter housing 46 a,b is influid communication with the valve switch 34 through flexible tubingextending from an outlet of the valve switch 34 to a quick disconnectcoupling such that filter housing 46 a,b can be disconnected from thevalve switch 34. Similarly, in each filter set 30, 32, the respectivefilter housing 48 a,b is in fluid communication with the outlet conduit44 through flexible tubing extending from a quick disconnect coupling atthe outlet portion 56 of filter housing 48 a,b to the outlet conduit 44.Within each filter set 30, 32, the filter housings 46 a,b, 47 a,b, 48a,b are connected in series using flexible tubing terminating at quickdisconnect couplings at either end portion of the respective filterhousing. The use of quick disconnect couplings to connect filterhousings 46 a,b, 47 a,b, 48 a,b in fluid communication with other partsof the plant 10 reduces maintenance time by improving access tocartridge filters in the filter housings 46 a,b, 47 a,b, 48 a,b.Additionally or alternatively, the flexibility of the tubing used toachieve fluid communication in the filter station 14 can facilitatemoving the filter sets 30, 32, for example, during initial configurationof the plant 10 or during maintenance.

The stand 36 supports the filter sets 30, 32 such that the respectiveelongate flow paths defined by the filter housings 46 a,b, 47 a,b, 48a,b are substantially vertical during operation of the plant 10. Becauseoff-the-shelf cartridge filters 49 are typically elongate, thissubstantially vertical orientation of the elongate flow paths of filterhousings 46 a,b, 47 a,b, 48 a,b can facilitate fitting the filterstation 14 within a size envelope that is amenable to portability. Forexample, this substantially vertical orientation can facilitate fittingthe filter station 14 within the envelope with dimensions of50″×40″×40″.

Referring to FIG. 3, a portion (e.g., an inlet portion 54 and/or anoutlet portion 56) of each filter housing 46 a, 47 a, 48 a of filter set30 is hinged to the stand 36 such that an unhinged portion of eachfilter housing 46 a, 47 a, 48 a can be tilted (e.g., to about a 45degree angle) about a horizontal axis. During use, the unhinged portionof each filter housing 46 a, 47 a, 48 a can be disconnected, and eachfilter housing 46 a, 47 a, 48 a can be independently tilted away fromthe stand 36 to improve, for example, accessibility of the cartridgefilters 49 disposed in the filter housings 46 a, 47 a, 48 a. Forexample, the independent tilting of each filter housing 46 a, 47 a, 48 acan facilitate replacement of a single cartridge filter 49 at a time.Thus, if two cartridge filters 49 of one of the filter sets 30, 32 areclogged, an operator can remove the clogged cartridge filters whileleaving the third cartridge filter in place. As compared to systems thatrequire replacement of all filters at once, the ability to replacecartridge filters 49 selectively can reduce the overall operating costof the plant 10. Additionally or alternatively, tilting the filterhousings 46 a, 47 a, 48 a away from the stand 36 can reduce the overallamount of space required to perform maintenance on the filter station 14(e.g., by reducing the vertical head space required to pull or installthe cartridge filters 49).

For the sake of clarity and ease of illustration, only the support offilter set 30 on stand 36 has been described. It should be noted,however, that filter set 32 is supported on stand 36 in an analogousmanner.

Referring to FIG. 4, the stand 36 is rotatable about a vertical axis tofacilitate positioning filter sets 30, 32 for ease of accessibility. Forexample, stand 36 can be rotated about a vertical axis duringconfiguration or reconfiguration of the plant 10 such that filterstation 14 can be moved to a corner while still allowing filter sets 30,32 to be positioned for access during maintenance. Stand 36 can lockinto place during operation of the plant 10 to reduce the likelihoodthat filter sets 30, 32 will move out of position.

Referring to FIG. 5, a controller 60 is in communication (e.g.,electrical communication) with the pressure sensors 50 a,b, 51 a,b, 52a,b, the valve switch 34, and an input device 62. During use, thecontroller 60 receives input signals from the pressure sensors 50 a,b,51 a,b, 52 a,b and the input device 62 (e.g., keyboard). The controller60 sends output signals to the valve switch 34. The controller 60controls the position of the valve switch 34 based at least in part onthe signals from the pressure sensors 50 a,b, 51 a,b, 52 a,b.Additionally or alternatively, the controller 60 can control theposition of the valve switch 34 based on the signal from the inputdevice 62. The controller 60 receives pressure measurements frompressure sensors 50 a,b, 51 a,b, 52 a,b. Based on these pressuremeasurements, the controller 60 can send a command signal to the valveswitch 34 to divert the continuous flow of slurry to another filter setas necessary to allow continuous operation of the plant 10.

FIG. 6 shows an example of a controller process 63 used to control theposition of the valve switch 34. The controller process includes a setupstage 64 and a monitoring stage 66.

In the setup stage 64, the controller 60 receives 68 input parametersrelated to slurry processing (e.g., through input device 62). The inputparameters include a first threshold pressure drop at which a warningsignal will be generated and a second threshold pressure drop, greaterthan the first, at which the valve switch 34 will be activated toredirect slurry flow between filter sets 30, 32. The input parametersalso include an initial time delay, during which the valve switch 34 ismaintained 70 in a fixed position to allow the plant 10 to reach steadystate operation.

Once the controller 60 determines 72 that the initial time delay haslapsed, the controller 60 enters the monitoring stage 66 in which thecontroller receives 74 pressure measurements from each sensor 50 a,b, 51a,b, 52 a,b associated with filter sets 30, 32. The controller 60determines 76 which filter set 30, 32 is filtering slurry based on themagnitude of the pressure measurements of the pressure sensors 50 a,b,51 a,b, 52 a,b associated with each filter set 30, 32. For example, thefilter set 30, 32 associated with pressure measurements approximatelyequal to atmospheric pressure is the filter set that is not in use. Thecontroller 60 checks 78 this determination with the last actual valveswitch 34 position sent by the controller 60. If the determined andactual valve switch 34 positions do not match, the controller 60 signals80 an alarm and shuts down 82 the plant 10.

For the filter set 30, 32 that is filtering slurry, the controller 60determines 84 the pressure drop across each filter housing 46 a,b, 47a,b, 48 a,b (e.g., across each cartridge filter 49) based on themeasurements received from pressure sensors 50 a,b, 51 a,b, 52 a,b. Thecontroller 60 compares 86 the pressure drop across each filter housing46 a,b, 47 a,b, 48 a,b to the first and second threshold pressure dropsentered during the setup stage 64. For example, the pressure drop acrossfilter housing 46 a can be determined by subtracting the pressurereading from pressure sensor 51 a from the upstream pressure readingfrom pressure sensor 50 a, and this pressure drop is compared to thefirst and second threshold pressure drops. If the pressure drop acrossall three cartridge filters 49 in a filter set 30, 32 is less than orequal to the first threshold pressure drop 88, the controller 60continues to monitor the pressure drop across the filter housings 46a,b, 47 a,b, 48 a,b. If the pressure drop across one of the filterhousings 46 a,b, 47 a,b, 48 a,b is between the first and the secondthreshold pressure drops 90, the controller 60 activates 92 a warningsignal (e.g., a visual alert) indicating which filter housing 46 a,b, 47a,b, 48 a,b is associated with the warning signal. If the pressure dropacross one of the filter housings 46 a,b, 47 a,b, 48 a,b is greater thanthe second threshold pressure drop, the controller 60 activates 94 thevalve switch 34 to direct the slurry flow to the other filter set 30,32. The controller 60 also indicates 96 which filter housing(s) 46 a,b,47 a,b, 48 a,b had the excessive pressure drop that caused theactivation of the valve switch 34.

In response to the indication 96 by the controller 60, an operator canopen one or more sides of the enclosure 38 to disconnect the flexiblefilter tubing connected to the appropriate filter housing(s) 46 a,b, 47a,b, 48 a,b. The operator can tilt the filter housing(s) 46 a,b, 47 a,b,48 a,b away from the stand 36 to replace the filter in the filterhousing(s) 46 a,b, 47 a,b, 48 a,b. While the operator is replacing thesefilters, a substantially continuous flow of slurry continues to flowthrough the filter set that is not being serviced.

Control process 63 can be implemented in digital electronic circuitry,or in computer hardware, firmware, software, or in combinations thereof.Controller 60 can be implemented in a computer program product tangiblyembodied or stored in a machine-readable storage device for execution bya programmable processor; and control process 63 can be performed by aprogrammable processor executing a program of instructions to performfunctions of the invention by operating on input data and generatingoutput. The control process 63 can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. Each computer program can be implemented in a high-levelprocedural or object oriented programming language, or in assembly ormachine language if desired; and in any case, the language can be acompiled or interpreted language.

Suitable processors include, by way of example, both general and specialpurpose microprocessors. Generally, a processor will receiveinstructions and data from a read-only memory and/or a random accessmemory. Generally, a computer will include one or more mass storagedevices for storing data files; such devices include magnetic disks,such as internal hard disks and removable disks; magneto-optical disks;and optical disks. Storage devices suitable for tangibly embodyingcomputer program instructions and data include all forms of non-volatilememory, including by way of example semiconductor memory devices, suchas EPROM, EEPROM, and flash memory devices; magnetic disks such asinternal hard disks and removable disks; magneto-optical disks; andCD_ROM disks. Any of the foregoing can be supplemented by, orincorporated in, ASICs (application-specific integrated circuits).

While certain embodiments have been described, other embodiments arepossible.

For example, while the controller 60 has been described as determiningpressure drop across each filter housing 46 a,b, 47 a,b, 48 a,b, otherembodiments are possible. For example, a controller can activate thevalve switch 34 based on the pressure drop across the overall filter set30, 32.

As another example, while each filter set 30, 32 has been described asincluding filter housings 46 a,b, 47 a,b, 48 a,b arranged in series,other embodiments are possible. The flexible tubing connected to thefilter housings 46 a,b, 47 a,b, 48 a,b can be reconnected and/orreplaced such that slurry flows through filter housings 46 a,b, 47 a,b,48 a,b in parallel.

As yet another example, while the filter station 14 has been describedas including two filter sets 30, 32, other embodiments are possible. Forexample a filter station can include three or more filter sets and avalve switch having a respective number of positions (e.g., threepositions if there are three filter sets). These additional filter setscan increase the amount of time that the plant 10 can be operatedwithout maintenance, which can reduce the operating cost of a continuousslurry blending plant.

As still another example, while each filter set 30, 32 has beendescribed as including three filter housings 46 a,b, 47 a,b, 48 a,b,other embodiments are possible. For example, each filter set can includetwo filter housings. As another example, each filter set can includefour or more filter housings. Additionally or alternatively, the firstfilter set can include a different number (e.g., a greater number) offilter housings than the second filter set.

As another example, while filter housings 46 a,b, 47 a,b, 48 a,b havebeen described as being connected in fluid communication with othercomponents of the filter station 14, other embodiments are possible. Forexample, substantially rigid pipes can connect filter housings to theother components of a filter station. These substantially rigid pipescan reduce the likelihood that leaks will develop over long periods ofsubstantially continuous operation.

As yet another example, while the filter station 14 has been describedas having an enclosure including wheels 58 and fitting within a50″×40″×40″ envelope, other embodiments are possible. For example, insome embodiments, a filter station 14 can include filter housings 46a,b, 47 a,b, 48 a,b dimensioned to support cartridge filters 49 havingan outer diameter of greater than about 2.5 inches and/or less thanabout 18 inches. In some embodiments, a filter station 14 can includefilter housings dimensioned to support cartridge filters 49 having alength of greater than about 1 inch and/or less than about 50 inches(e.g., about 10 inches, about 20 inches). In certain embodiments, afilter station can be dimensioned for bench top filtration includingcartridge filters 49 having a length of about 10 inches. Additionally oralternatively, a bench top filter station can include an enclosure thatsits substantially flat (e.g., without wheels) on the bench top toreduce the likelihood that the bench top unit can be inadvertentlymoved. In some embodiments, a bench top filter station can include anenclosure having one or more handles to facilitate positioning the benchtop filter station.

As another example, while the filter station 14 has been shown as havingpressure sensors 50 a,b, 51 a,b, 52 a,b extending substantially parallelto the elongate flow path defined by the respective filter housings 46a,b, 47 a,b, 48 a,b, other embodiments are possible. For example,pressure sensors 50 a,b, 51 a,b, 52 a,b can be mounted at an angle(e.g., about a 45 degree angle) to the elongate flow path such that eachpressure sensor extends away from the stand 36. Such angled pressuresensors can facilitate tilting filter housings 46 a,b, 47 a,b, 48 a,bwithout interference from other components (e.g., other filter housingsor the stand).

As still another example, while the filter station 14 has been describedas having pressure sensors 50 a,b, 51 a,b, 52 a,b in communication withfilter housings 46 a,b, 47 a,b, 48 a,b, other embodiments are possible.For example, a filter station can include one or more of the followingmeasurements downstream of each cartridge filter to indicate whether therespective filter is clogged: pH; large particle counting (LPC), andconductivity.

As yet another example, while pumps 18, 19, 20, 21 have been describedas electro-mechanical diaphragm pumps, other embodiments are possible.For example, pumps 18, 19, 20, 21 can be bladder pumps. Each bladderpump includes a bladder disposed in a filter housing. During use, rawmaterial is drawn into the bladder as it expands under vacuum pressureexerted outside of the bladder, between the bladder and the filterhousing. With raw material in the bladder, pressurized fluid (e.g., air)is introduced outside of the bladder, between the bladder and the filterhousing. The pressurized fluid collapses the bladder to force the rawmaterial out of the bladder and into the processing stream. Withoutmechanical actuation, such bladder pumps are reliable over the longperiods of substantially continuous operation that are possible with thefilter station 14. The bladder pump can be, for example, a NOWPAK®container assembly available from ATMI, Inc. of Danbury, Conn.

As still another example, while the mixing station 12 has been describedas including flow controller 22, 23, 24, 25, each including anadjustable orifice and an internal regulating valve, other embodimentsare possible. For example, a mixing station can include a U-tube flowcontroller including a reservoir and an adjustable U-tube. Theadjustable U-tube is positionable to set the maximum level of fluid inthe reservoir. During use, fluid will continue to collect in thereservoir until the fluid level reaches the apex of the U-tube. Once thefluid in the reservoir reaches this level, additional fluid added to thereservoir will flow out of the reservoir through the U-tube (e.g., intoan overflow volume to be recycled back into the system). Withoutmechanical actuation, U-tube flow controllers are reliable over the longperiods of substantially continuous operation that are possible with thefilter station 14. An example of a U-tube flow controller is the U-Tubetechnology available from ChemFlow Systems, Inc. of San Jose, Calif.

While filter station 14 has been described as processing a CMP slurryused in semiconductor fabrication, a filter station can be used tofilter any of various different types of fluids used in any of variousdifferent industries. For example, a filter station can includestainless steel filter housings and be used to filter milk during dairyprocessing.

1-20. (canceled)
 21. A fluid processing method comprising: receiving asubstantially continuous flow of chemical mechanical planarizationslurry through a first plurality of filters; redirecting thesubstantially continuous flow of slurry to a second plurality of filterswhile the substantially continuous flow of slurry continues to flow; anddirecting the substantially continuous flow of slurry to a productpackaging station.
 22. The fluid processing method of claim 21, furthercomprising performing maintenance on the first plurality of filterswhile the substantially continuous flow of slurry flows through thesecond plurality of filters.
 23. The fluid processing method of claim22, wherein performing maintenance on the first plurality of filterscomprises responding to an indication of an excess pressure dropassociated with the first plurality of filters.
 24. The fluid processingmethod of claim 22, wherein performing maintenance on the firstplurality of filters comprises replacing the first plurality of filters.25. The fluid processing method of claim 21, wherein redirecting thesubstantially continuous flow of slurry to a second plurality of filtersis based at least in part on a measured parameter associated with atleast one filter of the first plurality of filters.
 26. The fluidprocessing method of claim 21, further comprising receiving an inputparameter, wherein redirecting the substantially continuous flow ofslurry to a second plurality of filters is based at least in part on thereceived input parameter.
 27. The fluid processing method of claim 21,wherein redirecting the substantially continuous flow of slurry to thesecond plurality of filters based at least in part on the measured fluidparameters associated with at least one filter of the first plurality offilters comprises comparing the measured fluid parameter to a thresholdvalue.
 28. The fluid processing method of claim 21, further comprisingproviding the substantially continuous flow of chemical mechanicalplanarization slurry upstream of the first and second plurality offilters.
 29. The fluid processing method of claim 28, wherein providingthe substantially continuous flow of chemical mechanical planarizationslurry comprises introducing a first material into a first materialfeed, introducing a second material into a second material feed, andmixing the first material and the second material.
 30. The fluidprocessing method of claim 28, wherein providing the substantiallycontinuous flow of chemical mechanical planarization slurry comprisesintroducing two or more materials into two or more respective materialfeeds, and mixing the two or more materials.
 31. The fluid processingmethod of claim 28, wherein providing the substantially continuous flowof chemical mechanical planarization slurry comprises adjusting thevolumetric flow rate of the first material and the volumetric flow rateof the second material.
 32. The fluid processing method of claim 31,wherein adjusting the volumetric flow rate of the first material and thevolumetric flow rate of the second material comprises independentlyadjusting the volumetric flow rate of the first material and thevolumetric flow rate of the second material.
 33. The fluid processingmethod of claim 32, wherein independently adjusting the volumetric flowrate of the first material and the volumetric flow rate of the secondmaterial comprises achieving a target concentration of the firstmaterial and the second material.
 34. The fluid processing method ofclaim 30, wherein the first material includes a chemically corrosiveagent and the second material includes abrasive particles.
 35. A fluidprocessing method comprising: introducing a first material into a firstmaterial feed and a second material into a second material feed; mixingthe first material and the second material into a substantiallycontinuous flow of chemical mechanical planarization slurry; adjustingthe volumetric flow rate of the first material through the firstmaterial feed and adjusting the volumetric flow rate of the secondmaterial through the second material feed; continuously filtering thesubstantially continuous flow of slurry; and receiving the substantiallycontinuous flow of slurry at a product packaging station.
 36. The fluidprocessing method of claim 34, wherein adjusting the volumetric flowrate of the first material through the first material feed and adjustingthe volumetric flow rate of the second material through the secondmaterial feed comprises achieving a target concentration of the firstmaterial and the second material in the slurry.
 37. The fluid processingmethod of claim 34, wherein receiving the substantially continuous flowof slurry at a product packaging station comprises controlling theposition of a valve switch in fluid communication with the substantiallycontinuous flow of slurry.
 38. The fluid processing method of claim 37,wherein controlling the position of the valve switch comprisescontrolling the position of the valve switch until the continuous flowof slurry reaches a steady state.
 39. The fluid processing method ofclaim 37, wherein controlling the position of the valve switch is basedat least in part on an input parameter received through an input device.40. The fluid processing method of claim 24, further comprisingintroducing the first material and the second material each into aplurality of material feeds.